public void AddWorkPlanElement() { IsWorkPlanElementEditVisible = true; EditedWorkPlanElement = new WorkPlanElement(); PrepareLists(); EditedWorkPlanElement.Room = RoomList.FirstOrDefault(); EditedWorkPlanElement.Class = ClassList.FirstOrDefault(); EditedWorkPlanElement.StartTime = TimeList.First(); EditedWorkPlanElement.EndTime = TimeList.ElementAt(1); EditedWorkPlanElement.Worker = Workers.FirstOrDefault(); _selectedOperation = CrudOperation.Create; }